Until early in this century it had been customary (and in certain writings it still is) for histories of science to speak of Galileo as the father of modern physics as though nothing preceded him, except the downfall of Aristotle. During the first two decades of this century Pierre Duhem devoted untiring energy to the study or "les précurseurs parisiens de Galilée". Among other significant discoveries, he thought that he had found in the theory of 'impetus' defended by Jean Buridan and his 'school' in the early and mid-fourteenth century the modern principle of inertia, which Galileo expressed by impeto, or momento. Constantine Michalski's studies on the theological movements of scepticism and criticism during the fourteenth century did not affect Duhem's thesis, but Michalski did point out that the Franciscan, Francis de Marchia, proposed the theory some years before Buridan. The acceptance of Duhem's thesis encouraged historians of science, a growing group, to see other points of similarity, and even identity, between the 'school' of Jean Buridan in the Parisian Faculty of Arts and the seventeenth century founders of classical physics.